Simultaneous assessment of intestinal permeability and lactase activity in human-milk-fed preterm infants by sugar absorption test: Clinical implementation and analytical method

BACKGROUND & AIMS

Experimental (nutritional) interventions in preterm infants frequently focus on intestinal maturation, as improving tolerance to enteral nutrition is a major goal. Intestinal permeability and lactase activity serve as markers for intestinal maturation. We aimed to develop a protocol for the simultaneous assessment of both markers in human-milk-fed preterm infants by a sugar absorption test. In addition, we developed a new gas chromatography-mass spectrometry (GC-MS) method for the analysis of lactulose, lactose, and mannitol in urine and milk collected during the sugar absorption test.

METHODS

The sugar absorption test was performed on days 4, 7, and 14 postpartum in 12 preterm infants (gestational age of 26-32 weeks). Human milk was collected, pooled, and divided into equal portions to provide a stable lactose intake for 24 h. Urine was collected in the last 6 h of this 24 h period, after administration of a bolus test sugar solution. Samples were analyzed by GC-MS after derivatization by oxime formation combined with acetylation.

RESULTS

The GC-MS method was validated and used for the accurate measurement of lactulose, lactose, and mannitol concentrations. The urinary lactulose/mannitol ratio declined with time, suggesting a decreased intestinal permeability. The urine-to-milk-lactulose/lactose ratio increased as a result of increased lactase activity with time.

CONCLUSIONS

The developed protocol for simultaneous assessment of intestinal permeability and lactase activity can be used to monitor the effect of experimental (nutritional) interventions in human-milk-fed preterm infants. Urine and milk samples obtained during the sugar absorption test can be accurately analyzed by GC-MS.

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.

The Microbiome, Intestinal Function, and Arginine Metabolism of Healthy Indian Women Are Different from Those of American and Jamaican Women

BACKGROUND

Indian women have slower arginine flux during pregnancy compared with American and Jamaican women. Arginine is a semi-essential amino acid that becomes essential during periods of rapid lean tissue deposition. It is synthesized only from citrulline, a nondietary amino acid produced mainly in the gut. The gut is therefore a key site of arginine and citrulline metabolism, and gut microbiota may affect their metabolism.

OBJECTIVE

The objective of this study was to identify differences in the gut microbiota of nonpregnant American, Indian, and Jamaican women and characterize the relations between the gut microbiota, gut function, and citrulline and arginine metabolism.

METHODS

Thirty healthy American, Indian, and Jamaican women (n = 10/group), aged 28.3 ± 0.8 y, were infused intravenously with [guanidino-15N2]arginine, [5,5-2H2]citrulline, and [15N2]ornithine and given oral [U-13C6]arginine in the fasting and postprandial states. Fecal bacterial communities were characterized by 16S rRNA gene sequencing.

RESULTS

In the fasting state, Indian women had lower citrulline flux than did American and Jamaican women [7.0 ± 0.4 compared with 9.1 ± 0.4 and 8.9 ± 0.2 μmol ⋅ kg fat-free mass (FFM)-1 ⋅ h-1, P = 0.01] and greater enteral arginine conversion to ornithine than did American women (1.4 ± 0.11 compared with 1.0 ± 0.08 μmol ⋅ kg FFM-1 ⋅ h-1, P = 0.04). They also had lower mannitol excretion than American and Jamaican women (154 ± 37.1 compared with 372 ± 51.8 and 410 ± 39.6 mg/6 h, P < 0.01). Three dominant stool community types characterized by increased abundances of the genera Prevotella, Bacteroides, and Bacteroides with Clostridium were identified. Indian women had increased mean relative abundances of Prevotella (42%) compared to American and Jamaican women (7% and < 1%, P = 0.03) which were associated with diet, impaired intestinal absorptive capacity, and arginine flux.

CONCLUSIONS

These findings suggest that dysregulated intestinal function and a unique gut microbiome may contribute to altered arginine metabolism in Indian women.

Assessment of the capability of a gelling complex made of tara gum and the exopolysaccharides produced by the microorganism Streptococcus thermophilus ST10 to prospectively restore the gut physiological barrier: a pilot study

BACKGROUND

Leaky gut, or intestinal permeability, is the phenomenon of the gut wall exhibiting increased absorbency. It is pretty well recognised that an altered or damaged bowel lining or gut wall may result from unbalanced diet, parasites, infection, or medications and that this allows substances such as toxins, microbes, undigested food, or waste to leak through. As a natural consequence, this prompts the body to initiate an immune reaction leading to potentially severe health conditions. Different strategies may be used to improve, at least temporarily, the physiological intestinal barrier. The use of specific beneficial microorganisms, such as lactobacilli and bifidobacteria, has been suggested as an innovative tool to counteract an improper level of intestinal permeability. The association of bacteria with specific gelling agents, such as gums, may represent an improvement since these molecules are able to form hydrophilic gels that distribute uniformly over the inner intestinal surface. This pilot study was undertaken to evaluate intestinal permeability in subjects treated with a gelling complex, an association of tara gum and the microorganism Streptococcus thermophilus ST10 (DSM 25246), which has a well-demonstrated in vitro ability to synthesise and secrete exopolysaccharides (EPSs).

METHODS

Twenty-five healthy subjects were enrolled in this human intervention, double-blind, placebo-controlled, pilot trial (age between 21 and 57 y, mean 37.7±11.2). Subjects were then randomised into 2 groups: group A (13 subjects) was given an active formulation containing 250 mg of tara gum and 1 billion viable cells of S. thermophilus ST10, whereas group B (12 subjects) was given a placebo formulation. All the subjects participating in the study were directed to take 1 dose per day for 30 consecutive days. The presence and concentration of exopolysaccharides (EPSs) in the faeces was determined at time 0 (d0), after 30 days of treatment (d30), and at the end of the 2-week follow-up period (d45). The monosaccharide composition of EPSs was used to quantify the possible contribution of tara gum to the amount of polysaccharides detected in the faecal material. Intestinal permeability was evaluated at the same time by means of the lactitol/mannitol ratio (small intestine permeability) and sucralose concentration (colonic permeability) in urine specimens sampled after specified times. A statistical comparison was made between the concentration of EPSs, the lactulose/mannitol ratio, and the amount of excreted sucralose in the 2 groups at d0, d30, and d45.

RESULTS

In the active group, supplementation with S. thermophilus ST10 and tara gum was able to significantly increase the faecal EPSs concentration compared with placebo (from 0.169 mg/g to 0.633 mg/g after 30 d, P<0.001). An interesting decrease in intestinal permeability, both of the small bowel and in the colon, was also recorded. The L/M ratio diminished from 0.021 in the active group to 0.014 and 0.015 after 30 and 45 days, respectively (P=0.045 and P=0.033 compared with placebo). The sucralose concentration decreased from 35.8 mg to 27.9 mg and 29.1 mg (P=0.038 and P=0.026 compared with placebo) at the end of the supplementation period and after the follow-up, respectively. No significant differences were recorded in the placebo after 30 days or at the end of the follow-up.

CONCLUSIONS

The association of the EPSs produced by S. thermophilus ST10 and tara gum seems capable of significantly improving the intestinal functional barrier in healthy subjects. A wider study in subjects presenting impaired gut permeability would be useful in the future to confirm the positive results from this pilot trial. In any case, our findings are consistent with the parallel increase in exopolysaccharide concentration in the faecal material, thus suggesting the effective ability of the strain used to secrete EPSs in the gut lumen. An innovative approach of this type may be useful in helping to restore the physiological barrier by means of a merely natural and mechanical action.

Comparison and validation of 2 analytical methods for measurement of urinary sucrose and fructose excretion

Urinary sugars excretion has been proposed as a potential biomarker for intake of sugars. In this study, we compared 2 analytical methods (gas chromatography [GC] and enzymatic reactions-UV absorption) for quantifying urinary fructose and sucrose using 24-hour urine samples from a randomized crossover controlled feeding study. All samples were successfully quantified by the GC method; however, 21% and 1.9% of samples were below the detection limit of the enzymatic method for sucrose and fructose, respectively. Although the correlation between the 2 methods was good for fructose (Pearson correlation, 0.71), the correlation was weak for sucrose (Pearson correlation, 0.27). We favor the GC method because of its better sensitivity, simplicity, and the ability to quantify fructose and sucrose directly in the same run. Of the 106 samples from 53 participants with complete urine collection after 2 study diets, 24-hour urinary fructose excretion was significantly associated with fructose intake. The sum of 24-hour urinary fructose and sucrose was significantly associated with total sugars consumption. However, variation in intakes of sugars explained only a modest amount of variation in urinary sugars excretion. In the unadjusted models, fructose intake explained 24.3% of urinary fructose excretion, and intake of total sugars explained 16.3% of the sum of urinary fructose and sucrose. The adjusted models explained 44.3% of urinary fructose excretion and 41.7% of the sum of urinary fructose and sucrose. Therefore, we caution using these biomarkers to predict sugars consumption before other factors that determine urinary sugars excretion are understood.

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.

Lyase activity of glycogen synthase: Is an elimination/addition mechanism a possible reaction pathway for retaining glycosyltransferases?

Despite the biological relevance of glycosyltrasferases (GTs) and the many efforts devoted to this subject, the catalytic mechanism through which a subclass of this large family of enzymes, namely those that operate with net retention of the anomeric configuration, has not been fully established. Here, we show that in the absence of an acceptor, an archetypal retaining GT such as Pyrococcus abyssi glycogen synthase (PaGS) reacts with its glucosyl donor substrate, uridine 5'-diphosphoglucose (UDP-Glc), to produce the scission of the covalent bond between the terminal phosphate oxygen of UDP and the sugar ring. X-ray diffraction analysis of the PaGS/UDP-Glc complex shows no electronic density attributable to the UDP moiety, but establishes the presence in the active site of the enzyme of a glucose-like derivative that lacks the exocyclic oxygen attached to the anomeric carbon. Chemical derivatization followed by gas chromatography/mass spectrometry of the isolated glucose-like species allowed us to identify the molecule found in the catalytic site of PaGS as 1,5-anhydro-D-arabino-hex-1-enitol (AA) or its tautomeric form, 1,5-anhydro-D-fructose. These findings are consistent with a stepwise S(N) i-like mechanism as the modus operandi of retaining GTs, a mechanism that involves the discrete existence of an oxocarbenium intermediate. Even in the absence of a glucosyl acceptor, glycogen synthase (GS) promotes the formation of the cationic intermediate, which, by eliminating the proton of the adjacent C2 carbon atom, yields AA. Alternatively, these observations could be interpreted assuming that AA is a true intermediate in the reaction pathway of GS and that this enzyme operates through an elimination/addition mechanism.

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.

Clinical trial: effect of active lactic acid bacteria on mucosal barrier function in patients with diarrhoea-predominant irritable bowel syndrome

BACKGROUND

The intestinal permeability is increased in patients with diarrhoea-predominant irritable bowel syndrome (D-IBS).

AIM

To determine the possible efficacy of lactic acid bacteria on the increased intestinal permeability in D-IBS.

METHODS

Treatment was employed for 4 weeks in a randomized single blind placebo controlled study with 30 D-IBS patients. Patients were given either probiotic fermented milk (Streptococcus thermophilus, Lactobacillus bulgaricus, Lactobacillus acidophilus and Bifidobacterium Longum) or milk beverage containing no bacteria. The clinical symptoms were scored and intestinal permeability was measured by a triple sugar test before and after treatment.

RESULTS

Small bowel permeability was measured as the ratio of lactulose and mannitol recovery and colonic permeability was measured as the total mass of sucralose excretion (mg). After probiotics treatment, small bowel permeability decreased significantly from 0.038 (0.024) at baseline to 0.023 (0.020) (P = 0.004), the proportion of patients with increased small bowel permeability was lower than baseline (28.6% vs. 64.3%, P = 0.023). However, colonic permeability improved neither in the probiotics group nor in the placebo group at week 4. Treatment with probiotics significantly decreased the mean global IBS scores compared with the baseline scores (9.62 +/- 1.05 vs. 7.64 +/- 1.24, P < 0.001).

CONCLUSION

Short-term active lactic acid bacteria treatment for D-IBS improved mucosal barrier function.

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.

Determination of mannitol and sorbitol in infusion solutions by capillary zone electrophoresis using on-column complexation with borate and indirect spectrophotometric detection

Capillary zone electrophoresis with indirect UV detection at 215 nm was applied for the separation and determination of mannitol (MA), sorbitol (SO) and xylitol in the form of anionic borate-polyol complexes. The separation was carried out in a fused silica capillary (total length 60 cm, effective length 50 cm, I.D. 50 microm) at 25 kV. The optimized background electrolyte was 200 mM borate buffer (pH 9.3, adjusted with triethylamine) containing 10 mM 3-nitrobenzoate as the chromogenic co-ion. The separation took approximately 13 min. The rectilinear calibration range was 0.2-2 mg mL(-1) for MA and SO when using xylitol (1 mg mL(-1)) as the internal standard. The limit of detection at a S/N of 3 was approximately 30 microg mL(-1) for either analyte. The method was used for the assay of MA or SO in pharmaceutical infusion solutions. The RSD values were 0.15% or 1.07% (n=6) when determining 100 mg mL(-1) of MA or 50 mg mL(-1) of SO in commercial infusion solutions. The results were in good agreement with those of pharmacopoeial iodimetric titration.

Resolution of common dietary sugars from probe sugars for test of intestinal permeability using capillary column gas chromatography

BACKGROUND

The most widely accepted method for the evaluation of intestinal barrier integrity is the measurement of the permeation of sugar probes following an oral test dose of sugars. The most-widely used sugar probes are sucrose, lactulose, mannitol and sucralose. Measuring these sugars using a sensitive gas chromatographic (GC) method, we noticed interference on the area of the lactulose and mannitol peaks.

METHODS

We tested different sugars to detect the possible makeup of these interferences and finally detected that the lactose interferes with lactulose peak and fructose interferes with mannitol peak. On further developing of our method, we were able to reasonably separate these peaks using different columns and condition for our assay. Sample preparation was rapid and simple and included adding internal standard sugars, derivitization and silylation. We used two chromatographic methods. In the first method we used Megabore column and had a run time of 34 min. This resulted in partial separation of the peaks. In the second method we used thin capillary column and was able to reasonably separate the lactose and lactulose peaks and the mannitol and fructose peaks with run time of 22 min.

RESULTS

The sugar probes including mannitol, sucrose, lactulose, sucralose, fructose and lactose were detected precisely, without interference. The assay was linear between lactulose concentrations of 0.5 and 40 g/L (r(2)=1.000, P<0.0001) and mannitol concentrations of 0.01 and 40 g/L (r(2)=1.000). The sensitivity of this method remained high using new column and assay condition. The minimum detectable concentration calculated for both methods was 0.5 mg/L for lactulose and 1 mg/L for mannitol.

CONCLUSION

This is the first report of interference of commonly used sugars with test of intestinal permeability. These sugars are found in most of fruits and dairy products and could easily interfere with the result of permeability tests. Our new GC assay of urine sugar probes permits the simultaneous quantitation of sucralose, sucrose, mannitol and lactulose, without interference with lactose and fructose. This assay is a rapid, simple, sensitive and reproducible method to accurately measure intestinal permeability.

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).

Studies on intestinal permeability of cirrhotic patients by analysis lactulose and mannitol in urine with HPLC/RID/MS

The method for separation and determination of lactulose (L) and mannitol (M) in urine was developed by HPLC with a refractive index detector (RID). The linearity ranged from 5 to 1000 microg/mL for L and M, respectively. Recoveries ranged from 93.1% to 97.1%. The intra- and inter-day relative standard deviations of peak area were between 0.8-1.4% (n=3) and 1.4-3.6% (n=3). The limits of detection were obtained with 1.40 microg/mL for L and 1.65 microg/mL for M. The ratios of L/M in the urine samples for the spontaneous ascitic fluid infection (SAI), sterile ascitic fluid (SA) patients, and healthy volunteers (HV) were determined. The results showed well the correlations among the L/M ratio, intestinal permeability (IP) and the illness status of patients, and also indicated lactulose could improve the IP of SAI patients. The peaks of L and M in chromatograms were identified by electrospray ionization/mass spectrometry (ESI/MS), which ensured the accurate measurement of the ratio L/M. This method presented a rapid, accurate, and practical technique for determining IP in clinical practice and investigating the pathology of hepatocirrhosis.

Long-Term Nutritional and Digestive Consequences of Pelvic Radiation

OBJECTIVE

To study long-term changes in nutritional status and gastrointestinal (GI) functions of 15 women previously treated with radiotherapy for gynecological cancer. Two years prior to this research, these patients had been assessed twice: before external radiotherapy and 5 weeks later, at the completion of the external dose (45-50 Gy).

METHODS

Each patient was given complete clinical evaluation, consisting of dietary, physical activity and digestive symptoms questionnaires. Blood was drawn for routine clinical laboratory tests (hemoglobin, white blood cell count, creatinine, lipoproteins, glucose, total proteins, albumin, and C reactive protein). Body composition was assessed by classical anthropometric indicators and double beam X-ray absorptiometry (DEXA), while muscle strength was measured through a hand dynamometer. Resting energy expenditure (REE), obtained by indirect calorimetry, was subtracted from energy ingestion, derived from dietary records, to calculate energy balance.

RESULTS

This third evaluation included fifteen patients. A significant increase in body mass index (BMI), % body fat and waist circumference were observed in comparison to earlier evaluations. The lean compartment decreased significantly, and REE descended in parallel. Meanwhile, total energy, fat and protein intake increased, compared to previous measurements. The changes in bowel habits observed during radiotherapy persisted at this third evaluation, with the exception of diarrhea, which was less reported. Abdominal bloating and rectal symptoms were the most prevalent complaints.

CONCLUSIONS

After radiation treatment for gynecological cancer, patients gained more body fat than expected in Chilean women around menopause. In spite of high protein ingestion, the loss of fat-free mass observed during radiation treatment was not recovered along with weight increase. This is probably associated with infrequent physical activity, both during and after treatment, and hyperphagia.

Gas chromatographic method for detection of urinary sucralose: application to the assessment of intestinal permeability

We developed a capillary column gas chromatography (CCGC) method for the measurement of urinary sucralose (S) and three other sugar probes including, sucrose, lactulose (L) and mannitol (M) for use in in vivo studies of intestinal permeability. We compared the capillary method with a packed column gas chromatography (PCGC) method. We also investigated a possible role for sucralose as a probe for the measurement of whole gut permeability. Sample preparation was rapid and simple. The above four sugars were detected precisely, without interference. We measured intestinal permeability using 5- and 24-h urine collections in 14 healthy volunteers. The metabolism of sugars was evaluated by incubating the intestinal bacteria with an iso-osmolar mixture of mannitol, lactulose and sucralose at 37 degrees C for 19 h. Sugar concentrations and the pH of the mixture were monitored. The use of the CCGC method improved the detection of sucralose as compared to PCGC. The average coefficient of variation decreased from 15% to 4%. It also increased the sensitivity of detection by 200-2000-fold. The GC assay was linear between sucralose concentrations of 0.2 and 40 g/l (r=1.000). Intestinal bacteria metabolized lactulose and acidified the media but did not metabolize sucralose or mannitol. The new method for the measurement of urinary sucralose permits the simultaneous quantitation of sucrose, mannitol and lactulose, and is rapid, simple, sensitive, accurate and reproducible. Because neither S nor M is metabolized by intestinal bacteria, and because only a tiny fraction of either sugar is absorbed, this pair of sugar probes appears to be available for absorption throughout the GI tract. Thus, the 24-h urinary concentrations of S and M, or the urinary S/M ratio following an oral dose of a sugar mixture, might be good markers for whole gut permeability.

Cellobiose and lactulose coupled with mannitol and determined using ion-exchange chromatography with pulsed amperometric detection, are reliable probes for investigation of intestinal permeability

Lactulose/mannitol and cellobiose/mannitol tests are currently used in the investigation of intestinal permeability (IP) in many gastrointestinal diseases. The aim of this study was to produce a good technique for the determination and comparison of the above-mentioned sugar probes to overcome the problem caused by the presence of significant glycosuria in patients affected by particular metabolic disorders such as diabetes mellitus. Tests were performed in 25 healthy volunteers, using either cellobiose (Ce) (5 g) and mannitol (Ma) (2 g), or lactulose (La) (5 g) and mannitol (2 g), given as oral isosmolar loads. Sugars were recovered in urine collected for 5 h. Analysis was carried out by using anion-exchange chromatography (AEC) with pulsed amperometric detection (PAD). Baseline separation of the above carbohydrates was achieved within 13 min by using a Carbopac PA-100 column and linear gradient elution. Carbohydrate quantification was performed by an internal standard method. The calibration curve for each sugar is linear to 40 mM. The limit of sugar detection is 0.01 mM. Recovery of sugar probes is between 98.2 and 100%. The %La, %Ce, %Ma in urine were evaluated and their ratios (Ce/Ma and La/Ma) were calculated. No significant difference in IP parameters were shown (La/Ma to Ce/Ma 0.018+/-0.014 vs. 0.012+/-0.007; the attendant probability of the null hypothesis being P=0.0714). Ce/Ma and/or La/Ma tests result similarly reliable in the clinical investigation of IP and the described new method is also helpful in urine even with high glucose concentration, without any interference.

Acute nutritional and intestinal changes after pelvic radiation

OBJECTIVE

Pelvic radiotherapy induces acute small bowel injury but its effects on nutritional status are unknown. The objective of this study was to prospectively evaluate nutritional, functional and morphologic intestinal changes, after radiotherapy.

METHODS

Fifteen patients were studied before and after pelvic irradiation. A clinical, nutritional and routine clinical laboratory assessment was performed. Nutritional parameters included dietary recall, subjective global assessment, anthropometric measurements (body mass index, skinfold thickness at four sites and circumferences of arm, waist and hip), hand grip strength, indirect calorimetry and Dual Energy X-ray absortiometry (DEXA). Intestinal parameters included permeabilty to sugars (assessed by lactulose and mannitol urinary excretion), intestinal transit time (measured by hydrogen breath test after ingestion of lactulose) and jejunal biopsies.

RESULTS

Thirteen patients presented diarrhea during radiation therapy. After five weeks, intestinal permeability increased, while intestinal transit time decreased. The second biopsy showed hypertrophy of villae and crypts. Simultaneously, patients lost weight at the expense of fat free mass. Resting energy expenditure was elevated prior to treatment and declined after five weeks. Changes in caloric ingestion were not significant.

CONCLUSIONS

Our results indicate that pelvic radiation induces a loss of fat free mass along with intestinal morphologic and functional changes.

Simultaneous HPLC determination with light-scattering detection of lactulose and mannitol in studies of intestinal permeability in pediatrics

We describe a new HPLC method for the simultaneous determination of lactulose and mannitol in urine, in which cation-exchange chromatography and evaporative light-scattering detection are used. The two sugars are orally administered for the estimation of intestinal permeability in children. Samples were purified by solid phase extraction on a C18 cartridge and subsequent addition of anion-exchange resin. Cellobiose may be used as an internal standard. The chromatographic separation was carried out in 16 min at a flow rate of 0.5 mL/min, using deionized water as the mobile phase. Within-run precision (CV) measured at three concentrations was 1.6–2.3% for lactulose and 1.0–1.9% for mannitol. Between-run CVs were 2.1–4.1% and 1.3–2.7% for lactulose and mannitol, respectively. Analytical recovery of both sugar probes was 97–101%. The detection limits (signal-to-noise ratio = 3) were 0.82 mg/L for lactulose and 0.65 mg/L for mannitol. The lactulose/mannitol ratio in control subjects was 0.024 ± 0.006; in patients with Crohn’s and coeliac diseases in active phase, the ratios were 0.200 ± 0.082 and 0.072 ± 0.025, respectively. The method is rapid, simple, and sensitive, and suitable for determination of intestinal permeability in children.